The placenta is a multifunctional organ of fetal origin, which is critical to normal fetal growth and development. In addition to direct fetal toxicity, ethanol may be toxic to the placenta as well. Ethanol-induced placental toxicity could contribute to the pathophysiology of alcohol related fetal injury. During the course of the current grant, this laboratory has characterized human placental trophoblasts in culture and demonstrated several alterations in cellular physiology. The human trophoblast is the principal functional cell of the human placenta, but it also expresses physiologic properties which are found in other human cell types. The ethanol-treated, cultured trophoblast model system, developed in this laboratory, enables evaluation of molecular biochemistry in readily available, nontransformed human cells. Using this system, we propose to test the fundamental hypothesis: Ethanol alters intracellular signal transduction. In particular, we will concentrate on the effect of ethanol on signal "cross-talk" mediated by protein kinase C (PKC), an important regulatory factor in normal intracellular signal transduction. This laboratory has shown that chronic exposure to ethanol, within a dose range found in man, results in enhancement of ligand-stimulated cAMP production by cultured trophoblasts. Preliminary data indicate that this alteration is not due to quantitative changes in G protein expression. Rather, there is an effective increase in adenylyl cyclase (AC) activity. We propose that this may be due, at least in part, to ethanol-induced activation of PKC and subsequent interaction of PKC with components of the adenylyl cyclase system. This proposal will investigate the biochemical basis for ethanol-induced enhancement of ligand-stimulated cAMP production in the context of PKC mediated signal "cross talk." Using the general model system of the cultured human placental trophoblast, exposed to ethanol in vitro, we propose to: Investigate ethanol-induced changes in components of the AC signalling system which are modulated by PKC "cross- talk;" Use inhibition of PKC to evaluate the role of PKC in ethanol- induced changes in the AC system; Evaluate the effect of ethanol on PKC activity, as it relates to the several phospholipases and diacylglycerol production; Determine the role of phosphatidylethanol as an activator of PKC and its role in signal "cross-talk." The studies should provide new information on the cellular mechanisms by which ethanol alters placental function and, hence, advance our understanding of the pathophysiology of the Fetal Alcohol Syndrome. Additionally, these findings should contribute to the general understanding of the mechanisms by which ethanol affects the biology of many human tissues, including those of the fetus.